Nearly 400 people have been killed after a powerful earthquake triggered a tsunami that hit Indonesia's central Sulawesi island. Latest reports reveal the casualty figure has climbed to at least 405 on Saturday evening, a government official said.

But according to some confirmed reports at least 384 people have been killed after a series of earthquakes and a tsunami struck the Indonesian island of Sulawesi, with hundreds more people feared dead as rescue workers scramble to reach the hardest hit areas.

A magnitude 7.5 earthquake was the strongest of the more than two dozen earthquakes that hit central Sulawesi on Friday, while a tsunami up to six metres high also struck coastal areas.

National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho said on Saturday afternoon that in addition to the 384 dead in Palu, the regional capital, 540 people have been injured and 29 people are missing.

"Many bodies were found along the shoreline because of the tsunami, but the numbers are still unknown," Sutopo Purwo Nugroho, a spokesman for the agency, told Reuters.

"When the threat arose yesterday, people were still doing their activities on the beach and did not immediately run and they became victims," he told a news briefing.

In Palu - home to around 350,000 people - partially covered bodies lay on the ground near the shore, the day after tsunami waves triggered by a 7.5 magnitude earthquake came ashore. Waves up to 3m (10ft) high swept through Palu on Sulawesi island.

Thousands of buildings have collapsed in Palu city, including the four-storey Antapura hospital, the eight-storey Roa-Roa hotel, a shopping mall and a bridge.

Indonesian authorities are working frantically to restore electricity and communications.

"The most important things to do right now are fixing the electricity, communications, sending in food, also food for children and babies, tents, drugs. We need drugs for field hospitals. We also need people to help the victims. That's why TNI and police have sent some 700 personnel, there are also some volunteers," Sutopo said.

Palu's main airport has sustained heavy damage to its runway and to its control centre. New navigation equipment for the airport was dispatched by helicopter from Makassar on Saturday morning.

Commercial flights to Palu were going to be suspended until October 4, with only emergency and humanitarian flights allowed to land, but the Indonesian government announced later on Saturday the airport would reopen for commercial flights on Sunday.

Smaller airports were still operating but are unable to receive heavy aircraft, while Palu's port was also damaged and the road between Poso and Palu has been blocked because of a landslide. A large ship was washed 70 metres inland by the wave.